Preparation and Investigation of Iron–Cerium Oxide Compounds for NO_<i>x</i> Reduction

The work was focused on investigating how Fe-doped CeO₂ composites affect the physicochemical properties in relation to the NO + CO reaction. The coprecipitation method was adopted to prepare CeO₂–FeO_<i>x</i> mixed oxides. The NO + CO reaction as well as temperature-programmed reduction, N₂ physisorption, oxygen storage capacity, X-ray photoelectron spectroscopy, X-ray diffraction, and in situ Fourier transform infrared spectroscopy were used to characterize the resulting samples. These results implied that the appropriate doping amount of FeO_<i>x</i> would cause an obvious change on the CeO₂ structure and properties. Also, the catalyst with the ratio of Ce:Fe = 1:0.35 showed the best catalytic properties. In addition, during calcination, adding a few FeO_<i>x</i> molecules could benefit the formation of low-valence Fe to a larger extent. This synergetic effect contributed to the formation of a larger number of Fe²⁺ and oxygen vacancies.